Influence of climate on radial growth of Pinus cembra within the alpine timberline ecotone

Radial growth variability and response to interannual climate variation of Cembran pine (Pinus cembra L.) were studied in the timberline ecotone on Mt. Patscherkofel (2246 m a.s.l.). The study area, which is in the inner alpine dry region of the Central Austrian Alps, is characterized by a continental climate with minimum precipitation in winter (about 150 mm during December-February) and frequent occurrence of warm dry winds (F?hn) in early spring. The hypothesis that spatial and temporal variability of radial growth is caused by site-related differences in sensitivity to winter stress (i.e., desiccation) was examined by applying dendroclimatological techniques. Ordination methods applied to tree ring time series revealed that spatial variability in radial growth is influenced by the local site factors elevation and slope aspect. Growth-climate relationships were explored using Pearson product-moment correlation coefficients and multiple regression analysis. Radial growth at the timberline was positively correlated with temperature in July and was also strongly correlated with mild temperatures in the previous autumn and high precipitation in winter (January-March). At the tree line, temperatures in the previous autumn and precipitation in late winter (March) also controlled radial growth, whereas July temperature was not significantly correlated with ring width. Because previous autumn temperature and winter precipitation were the main growth-determining factors at the timberline and the tree line, and both of these climate variables are known to influence susceptibility of trees to winter stress, the results support the working hypothesis. Analysis of climatic conditions in extreme growth years confirmed the high sensitivity of tree ring growth to precipitation in late winter (March) at the tree line plots. Furthermore, extent of growth reduction and release varied spatially and temporarily, with south- and west-facing stands showing a higher sensitivity to climate variation in the most recent decade (1990s) than the north-facing stand. This aspect-related change in sensitivity to climate may be associated with effects of climate warming on cambial activity.     

Influence of umbrella pine (<Emphasis Type="Italic">Pinus</Emphasis><Emphasis Type="Italic">pinea</Emphasis> L.) stand type and tree characteristics on cone production

Most umbrella pine (Pinus pinea L.) stands are managed as agroforestry systems, whose main production is fruit, due to the edible and highly nutritious kernels, and are frequently associated to natural or seeded pastures and grazing. The stands have low density, in order to enhance crown growth and fruit production. Nevertheless, cone production, both with regard to number and weight, varies greatly between stands, trees and years. In this study were selected three agroforestry systems, representative of umbrella pine stands whose main production is fruit, and one stand representative of the timber production system, where fruit is the secondary production. It was evaluated the variability in cone production as a function of the tree’s diameter at breast height and crown diameter and the individual tree’s competition status. The results indicate that stands managed in agroforestry systems with lower competition and individuals with larger diameter at breast height and crown diameter tend to produce more and heavier cones per tree. The first two principal components of the principal component analysis explain 84 % of the variance in cone production, trees’ dimensions and competition index. Tree competition status has a negative impact on production per tree.     

Influence of region of provenance and climate factors on wood anatomical traits of <Emphasis Type="Italic">Pinus nigra</Emphasis> Arn. subsp. <Emphasis Type="Italic">salzmannii</Emphasis>

Region of provenance is defined as an area with uniform ecological conditions where stands with similar phenotypic or genetic features are found. This study assesses the effect of differing climate conditions of eight Spanish regions of provenance of Pinus nigra Arn. subsp. salzmannii on earlywood anatomical traits measured in samples from basal discs from mature trees. Results showed that variation in wood biometry between provenances was high and more pronounced than intrapopulation variation. When comparing P. nigra with other Mediterranean pines, high intertracheid wall strength values are associated with better adaptation of pines to arid conditions. However, the intraspecific variations of this parameter in P. nigra did not follow the same pattern, due to the influence of mechanical support requirements. Trees subject to greater aridity were characterised by short tracheids, apparently resulting from their poorer growth, and high frequency of rays and ray parenchyma cells, which would allow trees to store greater amounts of starch, which is the source of metabolites invested in minimising the limitations imposed by water stress. Severe winter cold spells were strongly associated with high axial resin canal frequency and large radial resin canals, creating a powerful, preformed defence system. Increased tracheid lumen involved an increase in the size of bordered pits, favouring sap flow between tracheids, in addition to an increase in the maximum diameter of cross-field pits, favouring the flow of water and metabolites between the axial and radial systems. The high influence of region of provenance on structural variation in P. nigra shows the importance of provenance in the selection of seed origin for reforestation.     

Faustmann in an uncertain policy environment

This paper deals with optimal forest rotation age and silvicultural investment under policy or regulatory uncertainty to which wasteful deforestation and lack of reforestation and afforestation efforts in the developing countries and loss of old growth forests and biodiversity in the developed countries are attributed. Incorporating a stochastic uncertainty factor into the familiar deterministic Faustmann formula yields a result that confirms with casual observations — when policy uncertainty is present, forest stands are harvested earlier and silvicultural investment is smaller than otherwise. The policy implication is that, in order to promote forest resource conservation, encourage afforestation and reforestation, and attack other forest-related problems effectively, the pervasive nature of policy uncertainty needs to be curbed.     

Timber quality and volume increment of advance growth and planted Pinus sylvestris

Timber quality and increment of Scots pines were analysed in two adjacent stands in northern Sweden. One stand originated from advance growth, and one from planted seedlings. Height increment of advance growth that was higher than 1.3 m when released was slow compared with advance growth lower than 1.3 m and planted trees. Timber quality of advance growth, > 1.3 m at release, was poor due to high incidence of stem damage, most likely inflicted during the logging operation. Potential timber quality of planted Scots pines was better among dominated than dominating trees. Volume production was more than twice as high in the plantation as in the stand originating from advance growth. Slash burning after clear felling had a positive effect on production in the plantation.     

Influence of silvicultural practices on twisting rust infection and damage in maritime pine,as related to growth

A three-year study was carried out on the influence of silvicultural intensification on infection and damage caused by Melampsora pinitorqua, the twisting rust fungus, in maritime pine, Pinus pinaster Ait. The silvicultural practices studied were phosphorus fertilisation, the mode of stand establishment (either seeds or plants), and pine density. Growth and nutrition variables were also measured. Infection and damage were the most important in the first two years, which could reflect higher resistance with aging. At the end of the experiment, when pines were 4 years old, the planted, fertilised pines turned out to be the most damaged and the tallest, while the sown, non-fertilised pines were the least damaged and the smallest. Final damage was mainly explained by the damage observed in the earlier years. Annual damage was significantly correlated with infection percentage, more closely in the first year of observation. Higher susceptibility of the planted pines was associated with better growth and was explained by a greater amount of susceptible tissues, Under our experimental conditions, this explanation could not be retained for the fertilisation effect. However, phosphorus fertilisation induced changes in the nutritional status of pines. A significant positive correlation was observed between the phosphorus and potassium content on one hand and the susceptibility and damage on the other hand. Density effects were seldom observed in the experiment, either on growth or susceptibility variables. The positive relation between pine growth and rust damage, as confirmed in this study, emphasises the need for an integrated management of intensively managed pine stands, taking into account the disease hazard.     

Comparison of stand structure and growth between artificial and natural forests of Pinus sylvestiris var, mongolica on sandy land

Mongolian pine (Pinus sylvestiris Linnaeus var. mongolica Litvinov) as a valuable conifer tree species has been broadly introduced to the sandy land areas in “Three North” regions (North, northwest and northeast of China), but many prob-lems occurred in the earliest Mongolian pine plantations in 7hanggutai, 7hangwu County, Liaoning Province (ZZL). In order to clarify the reason, comprehensive investigations were carried out on differences in structure characteristics, growth processes and ecological factors between artificial stands (the first plantation established in ZZL in 1950s) and natural stands (the origin forests of the tree species in Honghuaerji, Inner Mongolia) on sandy land. The results showed that variation of diameter-class distributions in artificial stands and natural stands could be described by Weibull and Normal distribution models, respectively.Chapman-Richards growth model was employed to reconstruct the growth process of Mongolian pine based on the data from field investigation and stem analysis. The ages of maximum of relative growth rate and average growth rate of DBH, height, and volume of planted trees were 11,22 years, 8, 15 years and 35, 59 years earlier than those of natural stand trees, respectively. In respect of the incremental acceleration of volume, the artificial and natural stands reached their maximum values at 14 years and 33 years respectively. The quantitative maturity ages of artificial stands and natural stands were 43 years and 102 years respectively. It was concluded that the life span of the Mongolian pine trees in natural stands was about 60 years longer than those in artificial stands. The differences mentioned above between artificial and natural Mongolian pine forests on sandy land were partially attributed to the drastic variations of ecological conditions such as latitude, temperature, precipitation, evaporation and height above sea level. Human beings‘‘ disturbances and higher density in plantation forest may be ascribed as additional reasons. Those results may be potentially useful for the management and afforestation of Mongolian pine plantations on sandy land in arid and semi-arid areas.     

中国造林再造林碳汇项目的优先发展区域选择与评价

阐述<京都议定书>框架下清洁发展机制造林再造林碳汇项目的重要意义和实施项目的特殊要求.根据国际规则和中国林业发展现状,依据1990年以来无林地状况、林木生长率、造林成本、生物多样性状况等指标,综合评价确定适合开展清洁发展机制下造林再造林碳汇项目的优先发展区域.     

迪庆州川西云杉造林技术

介绍川西云杉生态、生物学特性.根据保存的人工川西云杉林成活及生长情况,认为迪庆州寒温带地区是川西云杉适生区,川西云杉是高寒山区天然林采伐后理想的迹地更新树种.藉此,对其种子采集、圃地选择、播种育苗、苗期管理、造林地选择、整地、造林方法、抚育管理、病虫害防治等一系列苗木培育及造林技术进行了阐述.     

The effects of pine mistletoe (Viscum album subsp. austriacum) on the growth of Scots pine and Crimean pine in Turkey

In this study, the effect of pine mistletoe (Viscum album subsp. austriacum) on basal area increment of Crimean pine and Scots pine was investigated. Dendrochronological data were collected from 223 (71 uninfected and 152 infected) Crimean pines and 195 (77 uninfected and 118 infected) Scots pines located in Kastamonu province of Turkey in 2014. Infected sample trees were classified as light, moderate or severe infection levels. Growth trends and basal area increment loses were compared between uninfected and infected trees for the periods of the last 10, 20 and 30 years. In addition, infection status of forest stands was investigated using temporary sample plots; 27 plots in Crimean pine stands and 26 plots in Scots pine. Results demonstrated that basal area increments were negatively affected by pine mistletoe for both species. Mean basal area increment losses of infected trees for the last decade were determined as 24% for Scots pine and 26% for Crimean pine. Basal area increment losses varied by infection levels (light, moderate and severe) as follows: 25%, 20% and 28% for Scots pines and 20%, 32% and 9% for Crimean pines. Scots pine stands were more severely infected by pine mistletoe than Crimean pine stands. There were negative correlations between number of infected trees and stand density for both species, while positive correlation was detected between the number of infected trees and mean diameter for Scots pine. The results of this study indicate that the pine mistletoe infection has negative effect on radial growth of Scots pine and Crimean pine trees. The results can be an important contribution to the forest management and protection activities in mistletoe-infected stands.     

江西省造林再造林碳汇项目发展潜力的评价指标探讨

文章对江西省清洁发展机制造林再造林碳汇项目发展潜力的评价进行分析研究,通过对土地资源、林木生长率、生物多样性、造林成本、农民收入等有关评价指标的分析,表明江西省实施CDM-AR项目具有明显的优势和巨大的潜力。     

Effect of Betula pendula Admixture on Tree Growth and Branch Diameter in young Pinus sylvestris Stands in Southern Finland

The effects of a birch admixture on the height and diameter growth and maximum branch diameter in planted Scots pine stands was studied using models constructed with a data set from 13 stands of 9–16 yrs of age and 2–8 m dominant height on average sites on mineral soils in southern Finland. The density and height of the birch varied highly between and within stands. Simulated results indicated that the pines were capable of keeping up in height growth with birches that had originated from seed. Even a very high number of birches (10?000 stems ha^?1) had virtually no effect on the height growth of the pines. The number of birches had a pronounced effect on the diameter growth and the maximum branch diameter in pine. Retention of a temporary birch component in young pine stands seems a feasible way of mitigating the adverse effects of low planting densities on the external quality of pine.     

Growth, healthy status and seed production of differently aged allochtonous and autochtonous Pinus mugo stands in the Giant Mts. over 30 years

Plant communities with Dwarf pine (Pinus mugo var. pumilio) form characteristic vegetation in the subalpine belt of the Giant Mountains (Krkono?e, Karkonosze and Riesengebirge, Czech Republic). This “island” of arcto-alpine tundra represents the northernmost edge of Dwarf pine natural range. We asked how concentration of sulphur in needles, growth, healthy status and fructification changed over three decades (1981–2011) with different air pollution in differently aged (45–120 years) autochtonous and allochtonous (introduced from the Alps) Dwarf pine stands. Different Dwarf pine stands above the alpine timberline were able to withstand 1980s, the period of heavy air pollution, without any decrease in growth rate or remarkable decrease in healthy status. Dwarf pine is thus highly tolerant to deposition of sulphur compounds. High concentration of SO₂ in the air positively affected sulphur concentration in needles and eliminated thus sulphur deficiency. Higher germination rate of seeds in 2000s in comparison with 1980s indicate that the air pollution could decrease germination ability of seeds. High insect outbreaks (by Thecodiplosis brachyntera and Neodiprion sertifer) in 1990s and 2000s caused decrease in needle year classes. As there was a gradual increase in mean annual temperature over years 1981–2011, Dwarf pine stands can be more and more endangered by insect outbreaks in the future. There was no remarkable difference between autochtonous and allochtonous stands in all measured growth, healthy status and fructification characteristics. To determine real effects of air pollution and insect outbreaks on Dwarf pine stands from year to year fluctuations, decade-long monitoring is necessary.     

Reforestation of degraded Kermes oak shrublands with planted pines: effects on vegetation cover, species diversity and community structure

This paper examines the results of plantings of the Mediterranean pine species, Pinus halepensis and Pinus pinea, in a degraded Mediterranean kermes oak (Quercus coccifera) shrubland in Northern Greece, which were accomplished in order to mitigate ecosystem degradation. Plant establishment and the vegetation differences between the degraded ecosystem’s previous state and the new state following reforestation were measured in order to evaluate the effect of reforestation. Monitoring of the seedling survival and growth of the planted species was carried out during the next five years. In the fifth year we conducted botanical inventories in 18 and 15 plots (50 m² in size) from the reforested and control area, respectively. Plant community parameters estimated were: vegetation composition, total plant cover, planted species cover, native woody, herb and grass species cover, plant species richness, Shannon-Weiner index, community structure and dominant plant height. P. halepensis exhibited higher survival and growth than P. pinea. The reforested area exhibited higher plant diversity, higher vegetation cover, taller plants and more complex community structures than the control area, which concludes that plantings of pines can be successfully used in degraded ecosystem reforestation projects, in areas with similar site conditions.     

Study of Priority Area Selection and Evaluation for Afforestation and Reforestation Project under CDM in China

This paper gives an expatiation on significance and specific requirements of developing afforestation and reforestation project under CDM in Kyoto Protocol. According to the international rules and the current forestry development situation in China, the priority area for CDM afforestation and reforestation （CDM A/R） project is finally found after scientific selection and assessment on indicators, including the non-forestland area in 1990, growth rate of tree, afforestation cost, biodiversity and community development. The outcome from the study provides a solid basis for finding and implementing CDM A/R carbon sequestration projects in China. The study also puts forward suggestions on the strategy to develop and manage CDM A/R projects in China     

Improving substrate fertility to enhance growth and reproductive ability of a <Emphasis Type="Italic">Pinus halepensis</Emphasis> Mill. afforestation in a restored limestone quarry

We have evaluated the effects of improving substrate fertility on the growth and reproduction of a P. halepensis plantation in a restored limestone quarry on a stony calcareous regolith (R plots). The natural substrate was supplemented by adding a 0.2 m layer of a fine textured soil (RS plots) or a sewage sludge amended soil (RSS plots). The treatments were performed when the pines were 7 years old, and tree growth (height and trunk and canopy diameter) was monitored over the subsequent 12 years. The reproductive status of the trees was also measured when the pines were 20 years old. Tree growth was proportional to the amount of soil nutrients: 12 years after treatment the mean height of the R, RS and RSS trees was 1.5, 3.1 and 6.2 m respectively and growth increases over the baseline were 76, 264 and 632%. The treatment also affected the age of onset of reproduction (15, 11 and 9 years, respectively), the average number of cones per tree (12, 43 and 61), and the amount of seeds per cone (37, 52 and 72), but did not modify the germination percentage of pine seeds (ca 71.5%). Soil organic carbon increased proportionally to the vegetation development, contributing to carbon sequestration. These results suggest that improving the nutritional status of the soil not only improves the growth of trees, but it also ameliorates their reproductive ability (earlier reproduction onset and larger seed crop size). Implications for soil restoration through afforestation are also discussed.     

Effects of aspect and slope position on growth and nutritional status of planted Aleppo pine (<Emphasis Type="Italic">Pinus halepensis</Emphasis> Mill.) in a degraded land semi-arid areas of Jordan

Plantation of open grazing lands with Pinus halepensis are the most widely used practices in afforestation and reforestation in Jordan and other semi-arid areas around the Mediterranean Basin. The effect of aspect North (N), South (S), East (E) and West (W) and slope position (upper, middle, lower and valley bottom) on growth of planted Aleppo pine, nutritional status, plantation on restoring, needle, forest floor, nutrients concentration and soil properties were studied in Jubilee forest in Rakeen area, south of Jordan. Tree height was significantly higher in W than N, S and E aspects which mainly due to better moisture and nutritional conditions. All growth parameters were obtained on valley bottom were significantly higher than all aspect slope position combinations due to accumulation of run off and depositions from upper towards middle, and finally in lower slopes. In general, pH and EC were significantly reduced and soil organic matter was significantly improved by Allepo pine plantations compared to unplanted areas. West and N aspects as well as valley bottoms showed better soil physical and chemical properties.     

元谋县潜在碳汇林业资源调查及低碳消耗利用的策略措施

指出了经过对元谋县潜在碳汇林业资源的调查以及对低碳资源消耗利用的分析研究,借助国家实施生态恢复工程、天然林保护工程、退耕还林工程和巩固退耕还林成果建设以及长江水土保持林工程等建设项目的机遇,加速了区内造林进度,增加了有林面积,提高了森林林分质量,增加了碳汇林业的储存量。提出了碳汇林业资源的保护措施,加快农村能源建设,利用沼气、太阳能等清洁能源循环再利用代替薪材,科学推广青饲料发酵生喂,全面推进农村电网改造,节柴改造,大力发展经济林果和科学管理、充分利用果树的秸秆修剪再生利用,减少了薪柴能源的消耗,迅速消灭森林消长赤字、促进长大于消,以减轻农村劳动强度,提高山区广大农民的生活质量,改变当地的生活环境,加快区域内的经济发展和生态环境建设,为推广创建碳汇林业资源,保护碳汇林业资源提供科学策略措施。     

Comparison of tree growth and undergrowth development in aerially seeded and planted Pinus tabulaeformis forests

Direct seeding is a less expensive practice than planting and has the potential to become a viable alternative to transplanting for afforestation and regeneration purposes. As an effective and a less costly regeneration method, aerial seeding has been applied with several tree species. As early as 1956, Chinese people engaged in aerial seeding and stands with a total of 2.97×10⁷ hm² have been developed up to 2004. Our study tested whether the growth of planted Chinese pine (Pinus tabulaeformis Carr.) seedlings and its undergrowth development in northwest aspects differ from that of aerially sown seedlings on the northern and northwestern aspects of slopes. In 2007, we collected data such as height, diameter at breast height (DBH), clear bole height and canopy widths of trees, abundance, coverage, and frequency of shrubs and herbs from 21-year-old planted Chinese pine stands on a northwestern aspect (PNW), aerially sown stands in a northwest aspect (ANW) and aerially sown stands in a northern aspect (AN). Results showed that the relation of crown area and mean DBH was best fitted by a double inverse model for the ANW and AN forests and by a quadratic model for the PNW forest. There was no difference in the growth between ANW and AN forests, while growth was significantly higher in the PNW forest than in the ANW and AN forests. That was consistent with the Sorenson diversity indices in the shrub and herb layers, indicating that there was a large number of the same species in both aerially seeded stands, although their locations were different. Both the number of species in the undergrowth and the Shannon-Wiener index in the shrub layer were higher in the PNW stands than in the ANW and AN stands. Dominant families for all three stands were Rosaceae and Compositae in the shrub and herb layer, respectively. The dominant species for all three stands was Spiraea pubescens in the shrub layer, while the dominant species was different from each other in the three stands. The discrepancy in diversity and composition of species in the herb layer show that herbs are sensitive to shrubs in the three forests. High mortality and skewed diameter distributions reflect severe competition and too high a density in the aerially seeded forests. Thus, aerial seeding is a viable and effective regeneration technique, but management practices, such as thinning, should be applied to these forests.     

Development of oaks (Quercus petraea (Matt.) Liebl.) emerged from bird-dispersed seeds under old-growth pine (Pinus silvestris L.) stands

In East Germany, there are a lot of areas covered by old pine stands. They are growing on soils, on which under natural conditions without anthropogenic impact mixed stands of oak (Quercus petraea (Matt.) Liebl.) and pine (Pinus silvestris L.), would form a natural forest. An important objective of ecological silviculture in these areas is to convert the pure pine stands into mixed oak–pine stands by using natural regeneration methods. A highly appreciated assistant in this connection is the European jay (Garrulus glandarius L.). The remarkable results of its work have been found by analyzing the natural regeneration in a few old pine stands in the forest district of Weißwasser in Saxony. Although mother trees of oak are very scarce there, natural regeneration of oak was found everywhere in the research area. The oak regeneration, undoubtedly created by the jay, amounted to at least 2000 oaks/ha. They were mainly distributed at random, while pine regeneration was aggregated in places where gaps in the pine canopy occurred. Oak regeneration was established much earlier than pine regeneration. Thus, oaks exceeded pines in age, height and diameter. The oaks were also superior to pines concerning height increment for the last three years. Thus, there is a good chance for oak to defend its prevailing role in the regeneration in the future. Probably, the next forest generation will be composed of oak and pine trees. The analysis of the quality of the oak regeneration shows that there is no substantial difference to artificially sown oak stands. This indicates that the European jay creates oak stands sufficiently both in number and quality.